This invention relates to a mask and an object to be exposed used in a micromachining apparatus, as well as to an exposure apparatus using the mask and the object.
Increasingly fine photolithography has become essential with the advancements that have been made in increasing the capacity of semiconductor memories, raising the speed of CPUs and increasing the density of integration thereof. In general, the limit on micromachining in photolithographic equipment is decided by the wavelength of the light used. Consequently, light of ever shorter wavelengths is being used in photolithographic equipment. Currently, lasers in the near ultraviolet range of wavelengths are being employed and it has become possible to perform micromachining on the order of 0.1 .mu.m.
Problems that must be solved in order to achieve micromachining on the order of less than 0.1 .mu.m with ever finer photolithography include shortening the wavelengths of lasers and the development of lenses for use in this wavelength region.
A micromachining apparatus using a scanning near-field optical microscope (referred to as an "SNOM" below) has been proposed as means for making possible micromachining on the order of less than 0.1 .mu.m using light. For example, there is an apparatus that subjects a resist to local exposure that exceeds the limit on the wavelength of light by using evanescent light that emerges from minute apertures having a size of less than 100 nm.
However, existent examples of lithographic equipment using the SNOM arrangement carry out micromachining in the manner of single strokes using a single machining probe (or several such probes). A problem encountered, therefore, is that throughput cannot be made very high.
A method proposed to solve this problem (see the specification of Japanese Patent Application Laid-Open No. 08-179493) includes providing an optical mask with a prism, causing light to impinge upon the prism at the angle of total reflection, and transferring the pattern of the optical mask to a resist at one time using evanescent light that emerges from the surface of total reflection.
With the full-wafer exposure apparatus relying upon evanescent light using a prism as described in the above-mentioned Japanese Patent Application Laid-Open No. 08-179493, it is vital that the spacing between the prism mask and the surface of the resist be set to less than 100 nm. In actuality, however, there is a limit upon the surface precision of the prism mask and substrate and it is difficult to achieve the spacing of less than 100 nm between the prism mask and resist surface over the entire surface of the prism mask. In addition, if there is even the slightest skew between the prism mask and substrate when aligning the same, it is difficult to achieve the spacing of less than 100 nm between the prism mask and substrate over the entire surface of the prism mask.
If the prism mask is adhered to the resist surface by forcibly pressing it against the surface under these conditions, the substrate may be deformed, causing irregularities in the exposure pattern, or the resist ay be partially crushed by the prism mask.
Accordingly, a method that has been considered involves forming the mask of a resilient material and elastically deforming the mask so as to conform to the shape of the resist surface, whereby the surface of the mask is adhered to the surface of the resist.
In order to bring the mask surface into adhering contact even with finer structures on the resist surface, it is desired that the mask be made thinner. In a case where the mask is peeled off the surface of the resist after the mask surface is adhered to the resist surface and exposure carried out, there are occasions where the mask is damaged owing to the adsorbability of the mask surface to the resist surface, or where the member forming the mask pattern peels off from the mask base material owing to adsorption to the side of the resist. These difficulties can cause a decrease in yield.